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536                       ARM GLAND OF HAPAL&MUR                      CHAP.

detail it may be stated generally that the anatomy of the brain of
this group confirms the classification which is adopted in this

A curious feature in the anatomy of the Lemurs, which they
share with animals so remote from them in the system as the
Edentata, is the breaking up of some of the arteries of the limbs
to form retia mirabilia ; nothing of the kind is known among
the other Primates.

Perhaps the most remarkable difference between the Lemurs
and the Anthropoidea, which are really in many respects more
closely allied than might be inferred from the above summary of
differences, is in the structure of the placenta. The Lemurs agree
with the Ungulates in having a non-deciduate placenta.

A curious feature confined to the sub-family Lemurinae was
first discovered by myself in Hapalemur ffriseus* On the
forearm (see Mg. 258) is an area of hardened skin, which, is
raised into spine-like processes, Fully developed, this organ is
characteristic of the male, the area being marked off in the
female, but without the spiny outgrowths. On removing the
skin a gland about the size and shape of an almond is brought
into view. In other Lemurs there is no modified skin, but a
small tuft of particularly long hairs, which are also present in
Hapalemur, and a small gland beneath the skin. The gland of
Scupaleinur may be comparable with a tract of hardened skin in
L&m/wr catta, which projects to a large extent and has been spoken
of as a " climbing organ."

An almost exactly similar tuft of spine-like outgrowths exists
upon the lower end of the ankle of Galago gwrnetti. The spines
are black and bent, just as they are in JETa$dl&mur. There
appears also to be a gland. This structure is not universal in
the genus Grcdago any more than is the patch of spines in the
genus Hapalemur.

In addition to this gland and to the patch of spines which
cover It, the same Lemur as well as Chirogaleus and certain
species of Lemur possess to the inner side of it a bundle of long
and stiff "bristles associated with unusually large sebaceous
glands ; these structures are, of course, not homologous with the
gland of the arm of Ifapaleffiur^ as they coexist in the same

1 ** On some Points in the Structure of JSapatemur griseus " Proc. Zool.   Soe.
1884, p. 301.